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Aeolian Sound
Aeolian sound or Aeolian tone is sound that is produced by wind when it passes over or through objects. History Historically, Aeolus was the Greek ruler of the winds, and the Ancient Greeks believed these sounds were the voice of Aeolus. The earliest known observations about Aeolian sounds from a "scientific" viewpoint were made by Athanasius Kircher in 1650. Physical cause An Aeolian tone is produced when air passes over an obstacle, resulting in trailing vortices with oscillatory behavior. These eddies can have strong periodic components, resulting in a steady tone. This phenomenon is the main topic of aeroacoustics; For air moving over a cylinder, empirical data shows that an Aeolian tone will be produced with the frequency : f_\ =\ \frac, where V is the air velocity, D is the diameter of the cylinder, and \mbox is the Strouhal number, which has a value of about 0.2. Notable occurrences Aeolian sounds can be produced in the rigging of a sail-powered ship. The vortex trails p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges. Acoustics Acoustics is the interdisciplinary science that deals with the study of mechanical waves in gasses, liquids, and solids including vibration, sound, ultrasound, and infrasound. A scientist who works in the field of acoustics is an ''acoustician'', while someone working in the field of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind
Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hours, to global winds resulting from the difference in absorption of solar energy between the climate zones on Earth. The two main causes of large-scale atmospheric circulation are the differential heating between the equator and the poles, and the rotation of the planet (Coriolis effect). Within the tropics and subtropics, thermal low circulations over terrain and high plateaus can drive monsoon circulations. In coastal areas the sea breeze/land breeze cycle can define local winds; in areas that have variable terrain, mountain and valley breezes can prevail. Winds are commonly classified by their spatial scale, their speed and direction, the forces that cause them, the regions in which they occur, and their effect. Winds have vario ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aeolus
In Greek mythology, Aeolus or Aiolos (; grc, Αἴολος , ) is a name shared by three mythical characters. These three personages are often difficult to tell apart, and even the ancient mythographers appear to have been perplexed about which Aeolus was which. Diodorus Siculus made an attempt to define each of these three (although it is clear that he also became muddled), and his opinion is followed here. * The first Aeolus was a son of Hellen and the eponymous founder of the Aeolian race. * The second Aeolus was a son of Poseidon, who led a colony to islands in the Tyrrhenian Sea. * The third Aeolus was a son of Hippotes who is mentioned in the ''Odyssey'' and the ''Aeneid'' as the ruler of the winds. All three men named Aeolus appear to be connected genealogically, although the precise relationship, especially regarding the second and third Aeolus, is often ambiguous as their identities seem to have been merged by many ancient writers. Aeolus was also the name of the fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greeks
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of culturally and linguistically related city-states and other territories. Most of these regions were officially unified only once, for 13 years, under Alexander the Great's empire from 336 to 323 BC (though this excludes a number of Greek city-states free from Alexander's jurisdiction in the western Mediterranean, around the Black Sea, Cyprus, and Cyrenaica). In Western history, the era of classical antiquity was immediately followed by the Early Middle Ages and the Byzantine period. Roughly three centuries after the Late Bronze Age collapse of Mycenaean Greece, Greek urban poleis began to form in the 8th century BC, ushering in the Archaic period and the colonization of the Mediterranean Basin. This was followed by the age of Classic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Athanasius Kircher
Athanasius Kircher (2 May 1602 – 27 November 1680) was a German Jesuit scholar and polymath who published around 40 major works, most notably in the fields of comparative religion, geology, and medicine. Kircher has been compared to fellow Jesuit Roger Joseph Boscovich and to Leonardo da Vinci for his enormous range of interests, and has been honoured with the title "Master of a Hundred Arts".Woods, p. 108. He taught for more than 40 years at the Roman College, where he set up a wunderkammer. A resurgence of interest in Kircher has occurred within the scholarly community in recent decades. Kircher claimed to have deciphered the hieroglyphic writing of the ancient Egyptian language, but most of his assumptions and translations in this field were later found to be incorrect. He did, however, correctly establish the link between the ancient Egyptian and the Coptic languages, and some commentators regard him as the founder of Egyptology. Kircher was also fascinated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aeroacoustics
Aeroacoustics is a branch of acoustics that studies noise generation via either turbulent fluid motion or aerodynamic forces interacting with surfaces. Noise generation can also be associated with periodically varying flows. A notable example of this phenomenon is the Aeolian tones produced by wind blowing over fixed objects. Although no complete scientific theory of the generation of noise by aerodynamic flows has been established, most practical aeroacoustic analysis relies upon the so-called '' aeroacoustic analogy'', proposed by Sir James Lighthill in the 1950s while at the University of Manchester. whereby the governing equations of motion of the fluid are coerced into a form reminiscent of the wave equation of "classical" (i.e. linear) acoustics in the left-hand side with the remaining terms as sources in the right-hand side. History The modern discipline of aeroacoustics can be said to have originated with the first publication of Lighthill in the early 1950s, when noise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strouhal Number
In dimensional analysis, the Strouhal number (St, or sometimes Sr to avoid the conflict with the Stanton number) is a dimensionless number describing oscillating flow mechanisms. The parameter is named after Vincenc Strouhal, a Czech physicist who experimented in 1878 with wires experiencing vortex shedding and singing in the wind. The Strouhal number is an integral part of the fundamentals of fluid mechanics. The Strouhal number is often given as \text = \frac, where ''f'' is the frequency of vortex shedding, ''L'' is the characteristic length (for example, hydraulic diameter or the airfoil thickness) and ''U'' is the flow velocity. In certain cases, like heaving (plunging) flight, this characteristic length is the amplitude of oscillation. This selection of characteristic length can be used to present a distinction between Strouhal number and reduced frequency: \text = \frac, where ''k'' is the reduced frequency, and ''A'' is amplitude of the heaving oscillation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helmholtz Resonator
Helmholtz resonance or wind throb is the phenomenon of air resonance in a cavity, such as when one blows across the top of an empty bottle. The name comes from a device created in the 1850s by Hermann von Helmholtz, the ''Helmholtz resonator'', which he used to identify the various frequencies or musical pitches present in music and other complex sounds.Helmholtz, Hermann von (1885), ''On the sensations of tone as a physiological basis for the theory of music'' Second English Edition, translated by Alexander J. Ellis. London: Longman ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Étude Op
An étude (; ) or study is an instrumental musical composition, usually short, designed to provide practice material for perfecting a particular musical skill. The tradition of writing études emerged in the early 19th century with the rapidly growing popularity of the piano. Of the vast number of études from that era some are still used as teaching material (particularly pieces by Carl Czerny and Muzio Clementi), and a few, by major composers such as Frédéric Chopin, Franz Liszt and Claude Debussy, achieved a place in today's concert repertory. Études written in the 20th century include those related to traditional ones (György Ligeti) and those that require wholly unorthodox technique (John Cage). 19th century Studies, lessons, and other didactic instrumental pieces composed before the 19th century are extremely varied, without any established genres. Domenico Scarlatti's ''30 Essercizi per gravicembalo'' ("30 Exercises for harpsichord", 1738) do not differ in scope fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frédéric Chopin
Frédéric François Chopin (born Fryderyk Franciszek Chopin; 1 March 181017 October 1849) was a Polish composer and virtuoso pianist of the Romantic period, who wrote primarily for solo piano. He has maintained worldwide renown as a leading musician of his era, one whose "poetic genius was based on a professional technique that was without equal in his generation". Chopin was born in Żelazowa Wola in the Duchy of Warsaw and grew up in Warsaw, which in 1815 became part of Congress Poland. A child prodigy, he completed his musical education and composed his earlier works in Warsaw before leaving Poland at the age of 20, less than a month before the outbreak of the November 1830 Uprising. At 21, he settled in Paris. Thereafterin the last 18 years of his lifehe gave only 30 public performances, preferring the more intimate atmosphere of the salon. He supported himself by selling his compositions and by giving piano lessons, for which he was in high demand. Chopin formed a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piano Sonata No
The piano is a stringed keyboard instrument in which the strings are struck by wooden hammers that are coated with a softer material (modern hammers are covered with dense wool felt; some early pianos used leather). It is played using a keyboard, which is a row of keys (small levers) that the performer presses down or strikes with the fingers and thumbs of both hands to cause the hammers to strike the strings. It was invented in Italy by Bartolomeo Cristofori around the year 1700. Description The word "piano" is a shortened form of ''pianoforte'', the Italian term for the early 1700s versions of the instrument, which in turn derives from ''clavicembalo col piano e forte'' (key cimbalom with quiet and loud)Pollens (1995, 238) and ''fortepiano''. The Italian musical terms ''piano'' and ''forte'' indicate "soft" and "loud" respectively, in this context referring to the variations in volume (i.e., loudness) produced in response to a pianist's touch or pressure on the keys: the grea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ludwig Van Beethoven
Ludwig van Beethoven (baptised 17 December 177026 March 1827) was a German composer and pianist. Beethoven remains one of the most admired composers in the history of Western music; his works rank amongst the most performed of the classical music repertoire and span the transition from the Classical period to the Romantic era in classical music. His career has conventionally been divided into early, middle, and late periods. His early period, during which he forged his craft, is typically considered to have lasted until 1802. From 1802 to around 1812, his middle period showed an individual development from the styles of Joseph Haydn and Wolfgang Amadeus Mozart, and is sometimes characterized as heroic. During this time, he began to grow increasingly deaf. In his late period, from 1812 to 1827, he extended his innovations in musical form and expression. Beethoven was born in Bonn. His musical talent was obvious at an early age. He was initially harshly and intensively t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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